The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 12, 2011
Filed:
Jul. 18, 2007
Naoto Shimada, Hyogo, JP;
Hiroaki Yamamoto, Hyogo, JP;
Naoki Nakanishi, Shiga, JP;
Masahiko Nishimoto, Osaka, JP;
Takuya Okuda, Kyoto, JP;
Naoto Shimada, Hyogo, JP;
Hiroaki Yamamoto, Hyogo, JP;
Naoki Nakanishi, Shiga, JP;
Masahiko Nishimoto, Osaka, JP;
Takuya Okuda, Kyoto, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An optical pickup device includes a diffraction gratingfor separating a light beam emitted from a semiconductor laser element into at least three light beams. The diffraction gratingis divided into three regions by a straight line extending in a direction parallel to a tangent line of a track of an optical information recording medium. A second regionB is divided into a first sub-blockand a second sub-blockby a straight line extending in a direction parallel to a radius direction of the optical information recording medium. The first sub-blockhas a phase difference of approximately 180 degrees from the second sub-block. The first regionA has a phase difference of approximately 90 degrees from the first sub-blockand has a phase difference of approximately 180 degrees from the third regionC.